1. Field of the Invention
The present invention relates to the general field of spectroscopic analysis, and more particularly, to the analysis of gas-phase materials and the surface of a wafer sample contained in a reaction chamber where beams of radiant energy are passed through the reaction chamber and caused to interact with the wafer sample or gas phase materials.
2. Description of the Related Art
The increased integration of semiconductor elements into electronic devices has prompted an increased need for lithography processes that are capable of achieving high aspect ratios and fine etching patterns. As a result, plasma etching processes for achieving high step difference, formation of fine patterns, and high anisotropic etching have gained in importance. In particular, processes for fabricating very large scale integrated devices, such as 256M DRAM's (Dynamic Random Access Memory) or more, require etching techniques that achieve high etching selectivity with respect to an underlying film, that minimize damage caused by plasma, and are capable of finely adjusting a pattern.
New plasma sources and new etching gases have been proposed in an effort to realize such an etching technique. In addition, research into ensuring optimal etching conditions through examination of etching reactions and appropriate control thereof is on-going.
Examination of the etching reactions involves in-situ analysis techniques for directly analyzing the wafer surface composition during a wafer etch process, observing behavior of adsorbing species, and analyzing the wafer surface chemical structure. However, current in-situ analysis techniques are ineffective because of the complexity of plasma and plasma disturbance, interference of surface discharge electrons caused by the plasma, and variation of energies.
Recent analysis techniques, including optical emission spectroscopy (OES) and laser induced fluorescence (LIF), have been proposed but these techniques can only analyze gas-phase plasma species. As such, there is a need for an analysis technique capable of directly analyzing the surface of a wafer as well as gas phase species during etching process.